For the past eight years, with a degree of doggedness, erudition and wit that would make one ardently wish to be on his side in a lawsuit, Jeffrey Steingarten has written about food for American Vogue. His topics are as various as low-fat cookbooks, the preparation of chips, or the seafood of the Venetian lagoon, and he will probably have lived, breathed, cooked and eaten every relevant permutation, along the way. "Of the 341 papers written on mashed potatoes in the past 20 years," this former corporate lawyer will announce, "30 seemed especially worth reading, as did Potato Processing, the bible of the industry."

When Steingarten says, "I have spent weeks combining the scientific journals for data on the poisons that lurk in every bowl of salad and every basket of crudites", you believe he has done little else during that time. Now his Vogue essays have been expanded and published as The Man Who Ate Everything (Headline, pounds 14.99) and include what must be the definitive account of trying to replicate Alsatian choucroute, living on a subsistence diet and cooking beef from cows that have been massaged and fed on sake.

Face to face, Steingarten is pretty much a stranger to soundbites. Still, any encounter with something to eat, however mundane, can set him off. Faced with a bottle of tomato sauce, he embarks on a discourse about how to identify ketchup made from fresh, ripe tomatoes by the date stamp on the lid. Apparently, most tomatoes picked for ketchup are turned into concentrate for future bottling, except those used at the time of the harvest in August. His flow of information is a force as dense and unstoppable as the contents of the upturned bottle.

Irrepressible in pursuit of the edible and a scourge of sloppy thinking and faddy eating, he doesn't just take pot shots at fashionable fears about fat, salt, sugar and raw shellfish, and those who fuel them, but launches a ruthlessly sustained assault on them, backed up by a mass of facts, none of which is irrelevant in his crusade against ignorance. You can learn from him that the best chips are fried in horse fat; that catfish have tastebuds on their whiskers; Pythagoras wouldn't let his followers eat fava beans; almost every low-fat recipe results in repulsive cakes; and his definition of fruit: an ovary we eat for dessert.

More seriously, he tackles the paradox that the French record for fatal coronary heart disease, the lowest in the Western world, confounds the arguments for reducing fat in our diets, and by his characteristically literal methodology - following them to the letter - he exposes the pointless denial of diet regimes.

Despite the title of his book, Steingarten's appetite for information is not matched by an indiscriminate one for food. He may live and work for food, but not for eating, which he does slowly and fastidiously. Steingarten is a heavyweight, but, miraculously, not of the type I expected before meeting him. Caroline Stacey